Featured Research

from universities, journals, and other organizations

Biomedical Engineers Advance On 'Smart Bladder Pacemaker'

Date:

February 19, 2007

Source:

Duke University

Summary:

Duke University biomedical engineering researchers
have moved a step closer to a "smart bladder pacemaker" that might one day
restore bladder control in patients with spinal cord injury or
neurological disease. The team's findings show that a device that taps
into the urinary "circuit" in the spinal cord could selectively coordinate
the contraction and release of muscles required for maintaining
continence.

Share This

Duke University biomedical engineering researchers have moved a step closer to a "smart bladder pacemaker" that might one day restore bladder control in patients with spinal cord injury or neurological disease.

Related Articles

The team's latest findings show that a device that taps into the urinary "circuit" in the spinal cord could selectively coordinate the contraction and release of muscles required for maintaining continence.

Warren Grill of Duke's Pratt School of Engineering and his colleagues have shown in cats that electrical stimulation can engage the spinal circuitry to effectively empty the bladder, while delivery of lower frequency pulses to the same nerve can significantly increase bladder capacity and improve continence.

In fact, manipulating the nervous system provides a more flexible way of influencing urinary function than would direct bladder stimulation, Grill said.

"Stimulating the bladder directly can cause it only to contract, not to keep it from contracting," Grill said. "We stimulate the sensory inputs in the spinal cord to orchestrate either the inhibition or activation of urination.

"This illustrates an important principle: we can use the 'smarts' of the nervous system to orchestrate control of complex functions," he said.

A similar approach might also have potential for stimulating the spinal reflexes that control locomotion, Grill added. Other investigators are testing such a system for use in physical therapy for people suffering from some form of paralysis, to help them learn to walk again.

Grill presented the team's findings on Friday, Feb. 16, at the annual meeting of the American Association for the Advancement of Science in San Francisco. His presentation was part of a symposium organized through the National Academies' Keck Futures Initiative. The research was supported by the National Institutes of Health and the Paralyzed Veterans of America Spinal Cord Research Foundation.

Ineffective emptying of the bladder can lead to complications, including damage to the bladder and frequent urinary tract infections, he said. Therefore, most people with spinal cord injuries are fitted with catheters that carry away urine.

The Duke researchers recently showed in cats that intermittent stimulation of the pelvic nerve that controls the urinary spinal circuitry emptied 65 percent of the bladder volume. The electrical pulses were delivered at a high frequency, mimicking the normal rate of sensory nerve impulses.

"We knew that the sensory fibers that excite the bladder normally fire at a rate of 30 to 40 impulses per second," Grill said. "We used the same rate to trick the circuit to turn on."

In another study, the researchers investigated the use of lower frequency electrical pulses for blocking unwanted bladder contractions. Earlier studies found that continuous low-frequency pulses of the pelvic nerve can suppress involuntary bladder contractions to maintain continence and increase bladder volume by 60 to 110 percent.

However, Grill suspected that the method could be made even more successful by making it more selective, delivering inhibitory pulses only in response to bladder contractions rather than constantly.

"The sensory system is designed to ignore signals if they are delivered constantly," Grill said. An everyday example of this "habituation" effect is the way people become accustomed to the pressure of a watch against the skin and no longer feel it, he said.

Indeed, the researchers found that inhibiting the urinary circuit only when contractions were detected increased bladder capacity by another 15 percent over continuous stimulation.

The researchers monitored bladder contractions indirectly by recording electrical nerve impulses, a sensing method that could be readily incorporated into a device resembling a pacemaker, Grill said.

"We relied on electrical recording of nerve activity that is coincident with bladder contraction to deliver a conditional inhibitory stimulus," Grill said. "It's a fully bioelectric and practical way to improve urinary continence."

The team now is working with Duke University Medical Center researchers on a clinical feasibility study to examine the urinary reflexes of human patients with spinal cord injuries.

Story Source:

The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.

More From ScienceDaily

More Health & Medicine News

Featured Research

Mar. 3, 2015 — Scientists have discovered a new hormone that fights the weight gain caused by a high-fat Western diet and normalizes the metabolism -- effects commonly associated with exercising. When tested in ... full story

Mar. 3, 2015 — New assays can detect malaria parasites in human blood at very low levels and might be helpful in the campaign to eradicate malaria, reports a new study. An international team led by Ingrid Felger, ... full story

Mar. 3, 2015 — Adults over the age of 30 only catch flu about twice a decade, a new study suggests. So, while it may feel like more, flu-like illness can be caused by many pathogens, making it difficult to assess ... full story

Mar. 3, 2015 — No significant change in home habits of smokers have been observed in the aftermath of a ban on smoking in public spaces, researchers report. Greater inspiration to kick the habit likely comes from ... full story

Mar. 3, 2015 — Heart function has been associated with the development of dementia and Alzheimer's disease through a new study. Participants with decreased heart function, measured by cardiac index, were two to ... full story

Mar. 3, 2015 — Children of recently separated or divorced families are likelier to drink sugar-sweetened beverages than children in families where the parents are married, putting them at higher risk for obesity ... full story

Mar. 3, 2015 — Gastric bypass and similar stomach-shrinking surgeries are a popular option for obese patients looking to lose weight or treat type 2 diabetes. While the surgeries have been linked to a decreased ... full story

Mar. 3, 2015 — Most people consume more salt than they need and therefore have a higher risk of heart disease and stroke, which are the two leading causes of death worldwide. But a new study reveals that dietary ... full story

Mar. 3, 2015 — Twice as many children born to mothers who took antibiotics during pregnancy were diagnosed with asthma by age 3 than children born to mothers who didn’t take prenatal antibiotics, a new study has ... full story

Featured Videos

Mom Triumphs Over Tragedy, Helps Other Families

AP (Mar. 3, 2015) — After her son, Dax, died from a rare form of leukemia, Julie Locke decided to give back to the doctors at St. Jude Children&apos;s Research Hospital who tried to save his life. She raised $1.6M to help other patients and their families. (March 3)
Video provided by AP

Looted and Leaking, South Sudan's Oil Wells Pose Health Risk

AFP (Mar. 3, 2015) — Thick black puddles and a looted, leaking ruin are all that remain of the Thar Jath oil treatment facility, once a crucial part of South Sudan&apos;s mainstay industry. Duration: 01:13
Video provided by AFP

Woman Convicted of Poisoning Son

AP (Mar. 3, 2015) — A woman who blogged for years about her son&apos;s constant health woes was convicted Monday of poisoning him to death by force-feeding heavy concentrations of sodium through his stomach tube. (March 3)
Video provided by AP

Related Stories

Oct. 17, 2014 — New research may lead to dramatically fewer bladder infections following spinal cord injuries and other traumatic injuries -- infections that can cause kidney damage, and even death, scientists ... full story

Aug. 6, 2013 — Scientists have shown that is possible to restore immune function in spinal injured mice. People with spinal cord injury often are immune compromised, which makes them more susceptible to infections. ... full story

June 25, 2013 — Using a novel technique to promote the regeneration of nerve cells across the site of severe spinal cord injury, researchers have restored bladder function in paralyzed adult rats, according to a new ... full story

May 30, 2010 — University of Alberta researchers have identified one of the body's natural self-repair mechanisms that kick in after spinal cord injury which could lead to the development of more effective ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.